SolarCity (NASDAQ: SCTY), Elon Musk’s other publicly-traded company, is a fascinating one because of its business model. On the surface, it is a manufacturer that also installs and services solar panels, yet SolarCity could be more like an automaker.

SolarCity is like an automaker because it makes money by leasing and financing solar systems to customers. Large automakers like Ford (NYSE: F) and Volkswagen (OTC: VLKAF) are swimming in cash because they have tens of millions of customers sending in car payments each month. Ford had $58.75 billion in cash and short-term investments on September 30, 2015, and Volkswagen reported having $42.13 billion in the bank on the same day.

Value investors should be interested in SolarCity because it could one day have millions of property owners sending in a payment each month. SolarCity reported having 262,495 customers at the end of second quarter 2015, an 86% increase over the same period in 2014, and $7.7 billion in contracted payments coming, according to GreenTechMedia. The amount of contracted payments was 132% higher in 2015 than in 2104.

Okay, so the potential to generate a lot of revenue is certainly there at SolarCity, but is it actually making money? The answer, unfortunately, is no.

SolarCity Is Not Making Money

The financial numbers demonstrate that SolarCity is actually losing money right now. On September 30, 2015, SolarCity reported the following dismal financial numbers:

A net income of -$66.51 million

A profit margin of -16.75%

A free cash flow of -$729.97 million

Cash and short-term investments of $418.37 million

-$661.83 million in cash and from operations

Right now SolarCity is far from profitable; in fact, its business is generating the opposite of float. Like Amazon.com and Tesla Motors (NASDAQ: TSLA), SolarCity is spending a lot of money right now in hopes of possibly making money in the future.

As at Tesla, Musk hopes that he will one day be able to generate a lot of float through lease and financing payments from SolarCity customers. Investors need to ask how realistic that assumption is. After all, solar systems and battery backup are not like cars; SolarCity cannot simply send the repoman out to pick one up if somebody stops making payments. It also has to pay to install and service those systems.

SolarCity’s Incredibly Growing Revenue

Well, there is one metric that seems to validate SolarCity’s business model, and it is revenue. SolarCity’s revenues have more than doubled in the past two years. In September 2013 SolarCity reported a TTM revenue of $140.06 million; that figure grew to $230.52 million September 2014 and $355.95 million in September 2015.

This means that SolarCity was able to add $125.43 million in revenue in a year. It also added $55.14 million in revenue in third quarter 2015 alone. In June 2015 SolarCity reported a TTM revenue of $300.43 million that grew to $355.95 million by September.

The revenue growth is incredible, but the cash from operations and cash and short-term investment figures show us that it is not creating any float—very much the opposite because it looks as if SolarCity has to spend several dollars to make one dollar.

This means that to actually make money, SolarCity will either have to greatly expand its customer base or greatly improve its efficiency and cut its cost of operations. SolarCity certainly has some opportunities; it is partnering with utilities and with Tesla.

Future Bright for SolarCity and Tesla Powerwall

Tesla’s Powerwall Home battery system a grid battery that does not necessarily need a solar system could become another source of revenue for SolarCity. Even one electric utility, Green Mountain Power in Vermont, is selling and leasing Powerwall systems to its customers, according to Forbes.

Since SolarCity already has a working relationship with Tesla (understandable because Elon Musk is the chairman of both companies), it is safe to assume that the solar panel company will become the chief distributor of Powerwall systems. There is a huge potential market for Powerwall systems out there because of the sheer unreliability of the U.S. electric grid.

The U.S. now suffers more power outages than any other developed nation, according to the U.S. Department of Energy and the North American Electric Reliability Corporation, an Off the Grid News article indicates. The number of blackouts is also increasing; the number of outages suffered by America’s aging power grid is 285% higher than it was in 1984.

This creates three potential markets for Powerwall and SolarCity systems:

Home battery backup, particularly for people who run home businesses and those who rely on medical devices that need electricity to stay alive. Like a lot of people who work from home, I’ve had the frustration of sitting there and watching as my dead computer gathers dust during a blackout while I should be using it to make money.

Grid backup for businesses (my local grocery store recently had to throw out tens of thousands of dollars’ worth of food because of a power outage that shut down refrigerators and freezers for several hours). With grid backup, the grocer could have kept both the coolers and the cash registers up and running and kept servicing customers and making money during the blackout.

Battery backup systems run by utilities themselves. A utility could set up a battery backup for a neighborhood or a town that experiences a lot of blackouts due to downed powerlines. Some utilities are also experimenting with storing electricity produced during off-peak hours for sale later in the day.

All this could help SolarCity because it could sell and service and, more importantly, lease and finance those systems. It could also increase its business by selling solar panels to the customers that use those systems. Walmart is already installing solar panels from SolarCity on the roofs of its stores and fulfillment centers in an effort that could become a model for other retailers.

SolarCity Is a Speculative Investment

As you can see, SolarCity could potentially be a huge cash cow for somebody, but right now it is not making money. Instead, SolarCity should be regarded as a highly speculative investment that might make money in the future.

If you are looking for a long-term energy play and you can afford a stock that does not make money for several years, SolarCity could be a good buy-and-hold play. If you need a stock that generates income right now, stay away from SolarCity for the foreseeable future and buy auto stocks like Ford and Volkswagen instead. Those companies are making major investments in electric vehicles and battery tech, and they do not lose money.